A lovely film about a Detroit singer-songwriter robbed of musical fame but rewarded with a second chance decades later, at age 70, "Searching for Sugar Man" tells a story of serendipity and just deserts. If it were fiction, it'd be improbable fiction. But it's fact, and the documentary (opening Aug. 10 in Chicago) made by a first-time Swedish filmmaker is introducing an international audience to a man called Sixto Rodriguez.

Today, as he did back when he was almost famous, he goes simply by Rodriguez. He was born in Detroit of Mexican immigrant parents and raised by his father after his mother died. Years later Rodriguez generated a following as that mysterious character who sang and played guitar, often with his back to the audience, in bars like the Sewer in the late 1960s.

His songs reminded people of Bob Dylan's. He wrote about the people of the streets, and his poetry — often grandiose in its imagery, but blessed with real power and a sensitive eye — sat well on his melodies. He got a record deal. He made two albums, "Cold Fact" and "Coming From Reality," the second one produced by a savvy veteran, Steven Rowland. High hopes and great expectations.

And neither album found an audience. Rodriguez's recording career was over before it began. He worked for decades in relative obscurity on construction jobs. He managed to feed his three daughters. He didn't realize until decades later that bootleg copies of "Cold Fact" had found their way to South Africa, as well as to Australia and New Zealand. He was huge in those places. But he never saw a penny from the sales there.

Meanwhile ... in 2006, Stockholm-based Malik Bendjelloul, of Algerian and Swedish ancestry, had saved up enough money from his work designing TV series title sequences to take six months off and travel, looking for short documentaries he might sell to the Swedish arts and culture show "Kobra," to which he was a contributor.

At a Cape Town, South Africa, record store, Bendjelloul heard a fantastic story from the owner about Rodriguez, his adoring fans in Cape Town, the impact songs such as "I Wonder" had on rebellious young South Africans of all races itching for apartheid to get lost. There were rumors that Rodriguez had committed suicide onstage after his final concert. The rumors were false, Bendjelloul was told. Using the relatively newfangled Internet, the owner of the record store, Stephen "Sugar" Segerman, in 1998 learned Rodriguez was alive and well and in Detroit. Not long afterward, Rodriguez came to Cape Town and gave the concert of his life. It is this story within the story that "Searching for Sugar Man" delivers so movingly, along with its portrait of a man who wasn't lucky. And then he was. (The title comes from a track on Rodriguez's "Cold Facts" album.)"We were in the Hamptons yesterday, for the film festival there," says Rodriguez over coffee recently in downtown Chicago. He and companion Bonnie Bulyk have seen a lot of the world since the film, which Sony Pictures Classics bought the day of its premiere at last year's Sundance Film Festival, took off on the festival circuit. "Bonnie's also from Detroit. She's seen a lot of stuff too. We travel together. She's very helpful." Rodriguez smiles. He has a serene way about him, and he knows philosophy, music and film (he favors John Cassavetes, among other directors). He calls "Searching for Sugar Man" director Bendjelloul "a true adventurer, and a good man."

In a separate interview, the director characterizes Rodriguez as "a mystery, still."

Now the mystery man is enjoying his second act. There's a Letterman appearance scheduled for Aug. 13. Rodriguez tours widely. He's been to South Africa four times, Australia four times.

"He's this humble, quiet guy," says Bendjelloul, "who never lost his hope. For 30 years, he was always walking with a guitar on his back in Detroit. He never played because no one asked him to play. But he wanted to play. And now he plays. It's beautiful. Think about it."

Rodriguez, in turn, credits the director with "exciting my musical career, and I'm grateful." The singer-songwriter has shared stages this year with Van Morrison and Ray Davies. The documentary that threatens to make this almost-famous man famous took its director four solid years to make on a shoestring (under a million, all in). When he told his father he was working initially for free, Bendjelloul says, the response he got was: "'You should stop now.' My parents were worried I wasn't getting paid. But everyone else said, no, keep going. It's the best story. And I was in love with it."

Rodriguez puts it simply, after a sip of coffee: "He's a self-taught filmmaker; I'm a self-taught musician." It was fate they met, just as something told the filmmaker to go into the Cape Town record store in 2006 and listen to a story about a Detroit legend who was more of a spirit, and who never got his due the first time.

Moral? According to Bendjelloul: If you're a documentary filmmaker looking for subjects, "See the world. It's so much better than sitting at home, Googling."

After 10 people were shot — seven of them in one incident — overnight in Baltimore following the city's most violent month in decades, police announced Sunday that 10 federal agents will embed with the city's homicide unit for the next two months.